1. Field of the Invention
The present invention relates to a device for optically analyzing a substance in blood using light and the nail as an optical window. The present invention also related to a device which for forming an orifice to administer a pharmaceutical composition for a cutaneous disease and/or a systemic disease via nail on the nail plate.
2. Background Art
Methods for measuring a blood glucose level by applying near infrared light through the skin and measuring transmitted light and scattered light of the near infrared light have been developed (see JP Patent Publication (Kokai) No. 10-325794 A (1998), JP Patent Publication (Kokai) No. 11-137538 A (1999), JP Patent Publication (Kokai) No. 2000-131322 A, JP Patent Publication (Kokai) No. 2003-245265 A, JP Patent Publication (Kokai) No. 2004-257835 A, JP Patent Publication (Kokai) No. 2004-321325 A, JP Patent Publication (Kokai) No. 11-216131 A (1999), JP Patent Publication (Kokai) No. 10-33512 A (1998)). The measurement of a blood glucose level using light has an advantage of offering less invasive and continuous measurement to a patient. However, recent studies on measurement of a blood glucose level with near infrared light by targeting the skin as a measurement site have reported that a measurement accuracy is up to ±25 to 50 mg/dl since light absorption by glucose is low (see K. Maruo, Applied Spectroscopy, vol. 57, No. 10, pp. 1236-44, 2003), in contrast to an effective measurement accuracy of glucose in practice: 100 mg/dl±10 mg. In particular, the measurement accuracy is low when a glucose level is as low as near 50 mg/dl. Therefore, it has been difficult to apply such a measurement device in order to prevent hypoglycemia. In addition, disturbing elements in the skin such as the adipose tissue and protein significantly affect the measurement. Therefore, it has been difficult to greatly improve measurement accuracy of a blood glucose level by applying near infrared light through the skin.
On the other hand, techniques to make holes on the nail plate for the treatment of a cutaneous disease such as a trichophytosis unguium and for using a nail as a drug delivering device to deliver a pharmaceutical composition systemically via nail orifices have been developed (U.S. Pat. No. 5,947,956, U.S. Pat. No. 4,180,058 and K. Maruo, Applied Spectroscopy, vol. 57 m no. 10, pp. 1236-44, 2003). However, a device which accurately makes a hole in a nail plate as deep as possible without damaging a nail bed has not been developed.